#grid-template-columns
default
grid-template-columns: none;
No columns are defined, so you only have one.
grid-template-columns: auto auto auto;
You can use the keyword auto so that each column resizes itself automatically.
grid-template-columns: 80px auto 1rem;
You can mix the units.
grid-template-columns: 40px 1fr 2fr;
You can use the fr flex unit to distribute the remaining space
across all flex columns.